Squint is a misalignment of the two eyes where both eyes are not looking in the same direction. This misalignment may be constant or may be present throughout the day or it may appear occasionally and the rest of the time the eyes may be straight; this is called as intermittent squint.

What causes squint?

The exact cause of squint is not known.

Six muscles control the movement of each eye (see picture). Each of these muscles acts along with its counterpart in the other eye to keep both the eyes aligned properly. A loss of coordination between the muscles of the two eyes leads to misalignment.

Sometimes a refractive error like hypermetropia (far sightedness) or an eye muscle paralysis may lead to deviation of the eye.

Poor vision in an eye because of some other eye disease like cataract etc. may also cause the eye to deviate. Therefore it is important in all cases of squint, especially in children, to have a thorough eye checkup to rule out any other cause of loss of vision.

What is 3D vision?

When both the eyes have good vision and are aligned properly, they focus on the same object. Each of the eyes sends a picture of the same object, viewed from a slightly different angle. These two images reach the brain where they are fused to form a single three-dimensional picture with depth perception. This is known as 3D vision. This gets affected in children with squint.

How is squint diagnosed?

Squint is diagnosed by an ophthalmologist specializing in that field. The doctor will do a few special tests to confirm the presence of squint and find out the reason behind the squint. In some cases there may be a false appearance of squint due to broad nasal bridge in a child. This is known as pseudo squint.